20001214024719A

(-23) The pilot reported to ATC, icing conditions and a problem with one of his engines. He told ATC that he was unable to maintain altitude and requested vectors to the nearest airport,een. The pilot flew the vectors initially, but later advised ATC that he was not able to reach the airport. Upon investigation of the a/c, found the left engine air filter about 1/2 covered with ice and the alternate air door closed. The right engine air filter was found charred and the alternate air valve was found in the open position. The top six plugs were removed and found black and sooty. (.4) prior to the flight, the pilot telephoned a flight service station. He was provided the current weather conditions along his route of flight, and advised of an AIRMET for occasional moderate rime or mixed ice in clouds and precipitation below 20,000 feet; and the freeing level at or near the surface. About 1 hour into the flight, at 8,000 feet, the pilot advised ATC that he had to descend. He stated that he thought he was picking up ice, and was having an engine problem. ATC vectored the flight to a nearby airport, but the pilot was unable to maintain altitude, and struck terrain about 7 miles from the airport. Examination of the wreckage revealed that the left engine air filter was partially covered with ice, which was about 1/2 inch thick. The filter was recovered after the post crash fire was extinguished. Further examination of the left engine revealed that alternate air valve was in the closed position, and the spark plugs were black and sooty. The airplane was equipped with some deice and anti-ice protection. However, according to the airplane manufacturer and a FAA inspector, the accident airplane and three similar airplanes used by the operator were not certified for flight into known icing. Additionally, none of the four airplanes met the requirements of FAR 135.227(c).